Boiling and Evaporation
Name: Elanggovan K.
What is the difference between boiling and evaporation?
Evaporation is a more general term. Evaporation means to change of a liquid into a vapor (gas).
It does not matter what the vapor pressure of the substance is. Water at 25 C has a vapor
pressure of about 25mm Hg. If a stream of dry air passes over the surface of the water it will
evaporate. Eventually there will be no liquid water remaining. On the other hand, "boiling"
usually refers to the temperature where the vapor pressure is 1 atmosphere = 760 mm Hg. In the
case of water this temperature is 100 C.
Depending on the conditions that produce them, in both processes molecules in the liquid state
are moved into the gaseous state. Evaporation is traditionally looked upon as the slower,
relatively quiescent case occurring at or near ambient temperature. Boiling, (a visually more
vigorous process) implies some externally applied heat source to speed up the evaporative
mechanism. Even so, the fundamental movement of liquid-to-the-vapor-state is essentially the
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Update: June 2012